Path: utzoo!attcan!uunet!bu.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!cs.utexas.edu!sun-barr!newstop!sun!imagen!atari!portal!cup.portal.com!R_Tim_Coslet
From: R_Tim_Coslet@cup.portal.com
Newsgroups: comp.sys.atari.st.tech
Subject: Re: How do I detect the presence of a carrier?
Message-ID: <35068@cup.portal.com>
Date: 20 Oct 90 08:32:46 GMT
References: <65827@iuvax.cs.indiana.edu>
  <1990Oct20.042911.7249@ns.network.com>
Organization: The Portal System (TM)
Lines: 20

John Logajan wrote...

>scr:  Some sort of syncronous data i/o port.

Actually this is a register to hold the "sync" character for syncronous
serial I/O. This character is sent automatically at the beginning of each
data transmission, and is used by the receiver to synchronize with the
recieved data.

In asynchonous modes this is not used (the start bit performs this function
instead, but needs to appear on each byte. You only need one "sync" character
per data block and a block might have thousands of characters)

Of course in synchronous mode you also need to send a clock with the data
and in asynchronous mode no clock is needed

                                        R. Tim Coslet

Usenet: R_Tim_Coslet@cup.portal.com
BIX:    r.tim_coslet